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A344843 The smallest of three consecutive integers that are products of three or more primes. 2

%I #57 Nov 18 2021 15:14:42

%S 98,124,152,170,174,188,230,242,243,244,284,342,343,350,368,374,404,

%T 423,424,428,434,440,474,475,494,506,530,548,574,594,602,603,604,608,

%U 636,637,638,644,650,656,663,664,710,714,724,728,740,774,775,782,804,824

%N The smallest of three consecutive integers that are products of three or more primes.

%H David A. Corneth, <a href="/A344843/b344843.txt">Table of n, a(n) for n = 1..10000</a>

%e 98 = 2*7*7, 99 = 3*3*11, 100 = 2*2*5*5. Three consecutive integers 98, 99, and 100 are each products of three or more primes. Thus, 98 is a term.

%t Select[Range[1002], Total[Transpose[FactorInteger[#]][[2]]] >= 3 && Total[Transpose[FactorInteger[# + 1]][[2]]] >= 3 && Total[Transpose[FactorInteger[# + 2]][[2]]] >= 3 &]

%t p3pQ[k_]:=Boole[#>2&/@k]=={1,1,1}; Position[Partition[PrimeOmega[ Range[ 900]],3,1],_?p3pQ]//Flatten (* _Harvey P. Dale_, Nov 18 2021 *)

%o (PARI) is(n) = for(i = 0, 2, if(bigomega(n + i) < 3, return(0))); 1 \\ _David A. Corneth_, Jun 08 2021

%K nonn

%O 1,1

%A _Tanya Khovanova_, Jun 07 2021

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Last modified September 18 10:16 EDT 2024. Contains 375999 sequences. (Running on oeis4.)